BMW 430 idling right rear tail has water sound.

1. When the engine is idling, the gas mixed with gasoline and air cannot be completely burned in the combustion chamber, resulting in abnormal noise in the exhaust pipe.

2. The vehicle has been idling for a long time, resulting in too much carbon and dirt on the throttle and air intake of the engine, and the area of the air intake passage has become smaller, which leads to abnormal noise when the driving computer control unit cannot accurately control the air intake.